is a ratio between two assets, most often a stock and a market average (index). This implementation uses the method described here and the second method described here to calculate its value: "To calculate the of a particular stock, divide the percentage change over some time period by the percentage change of a particular index over the same time period". This indicator oscillates around zero. If the value is greater than zero, the investment has been relatively strong during the selected period; if the value is less than zero, the investment has been relatively weak. The period and the comparative symbol can be set in the settings for the indicator (the defaults are 50 and SPX ), there you can also find an option to turn on a moving average.
Update to Pine Script Version 4 and add resolution to study.